In a randomized clinical trial of succimer, an oral chelating agent that lowers blood lead concentration, children with blood leads of 20 to 44 micrograms per deciliter were given succimer or placebo when they were about 2 years old and followed with cognitive and behavioral testing. We reported previously that, despite lower blood lead levels during treatment, children given succimer had test scores that were no different from those of children given placebo at ages five or seven years. This year we reported that, although succimer is generally not toxic, the children given succimer were 5 mm or so shorter at ages five and seven than the children given placebo. The results of this trial (among other things) have affected policy, in that primary prevention, rather than treatment, is becoming the standard approach to childhood lead poisoning. Because of our involvement with the trial, we were asked last year by the New England Journal and this year by Pediatrics to comment on the policy and practice implications of new data showing toxic effects of lead at levels lower than previously reported. In addition, we had a Fulbright fellow from Poland examining the general question of screening children for lead poisoning from an international perspective. When we compared the situation in Poland to that of the US, we found that it was necessary to have age-specific distributions of blood lead or at least the age-specific prevalence of elevated blood lead concentrations to know whether to expect a US style program to work. Analysis of data from the Silesia region in Poland showed that the age-specific prevalences of childhood lead poisoning were different from the US, with Polish children having higher blood lead concentrations achieved later, at about age 3 to 4, than the children in the US.